Need some help with meshes

Hi. This happens because the garment is too tight. This is not something you have to worry though, because all places of the body the garment covers should be deleted.
It's best to start learning how to make clothing not from trying yourself or following one tutorial, but from going through as many start-to-finish tutorials as you can find to get a good idea of what has to be done and for what reason. A tip: look at the requirements and where the author puts uvs in the uv_0 map. If they tell you to download 2 version of Blender (2.7 and 2.78) and put the uvs in the bottom right corner, it's best to find another tutorial. Those tend to be identical and outdated